With the emergence of the electric car, people start questioning the environmental impact of electric cars, in particular the CO2-emissions. Below you will find an article, based on scientific research, on the CO2-emissions of electric cars and how they compare to gasoline and diesel cars.
WTW, WTT en TTW
When CO2-emissions are discussed, often the following abbreviations are used: WTW, WTT and TTW. Figure 1 shows the meaning and content of each abbreviation.
CO2 emissions electricity, gasoline and diesel
CO2 emission factors are factors that are being used to calculate the CO2 emissions for organisations and activities. An example of a CO2 emission factor is the Well-to-Wheel (WTW) emission of 2.740 grams of CO2 for every liter of Dutch gasoline (co2emissiiefactoren.nl, January 2015).
The Dutch website http://co2emissiefactoren.nl/ was founded by SKAO, Stimular, Connekt Milieu Centraal, the central government and various experts. This website contains a large database of CO2 emission factors. Table 1 shows the relevant CO2 emission factors for cars.
The Dutch gray energy is, for approximately 30%, generated by coal, the rest is generated by natural gas and nuclear power. The average Dutch energy mix is a mixture of, i.a., coal, natural gas, nuclear power, biomass, solar, wind and hydropower (CBS, February 2015).
CO2 emissions usage car
When the CO2 emissions of a car are calculated, usually only the direct emissions are being taken into account. The New European Driving Cycle (NEDC) only considers the direct emissions and therefore only the Tank-to-Wheel (TTW) emissions. This is the reason for fully electric cars to be publicized as zero-emission. In order to make a fair comparison between electric and fossil fuel cars, the indirect (WTT) emissions should be taken into account as well.
To compare electric cars with fossil fuel cars, the CO2 emissions of three electric cars have been calculated. The three electric cars are the Tesla Model S P85, the Nissan Leaf (24 kWh) and the Renault Zoe. These three cars are the best sold electric cars in The Netherlands (Yushift.com, 20 January 2016) and these specific versions have been tested by EcoTest (EcoTest, 13 January 2015). The new versions of the Tesla Model S (the 90D, 85D and 70D) are more efficient, but since EcoTest has not tested these versions yet, they are not included. When the CO2 emissions of the electric cars have been calculated, the fuel consumption of gasoline and diesel cars, that cause similar emissions, can be calculated in litres per 100 kilometer.
The consumption per 100 km for the three electric cars, including load loss, can be found in table 2.
The EcoTest data is used for the energy consumption. The EcoTest is performed in Germany and takes into account the load loss of charging electric cars by reading out the used energy by the charger (EcoTest, 13 January 2015).
To calculate the CO2 emissions of the electric cars, the information in table 1 and table 2 can be combined. Table 3 provides an overview of the CO2 emissions and a comparison of the fuel consumption of gasoline and diesel cars to match the emissions of electric cars.
Table 3 shows the difference in CO2 emissions between electric cars and cars running on fossil fuel. The difference between gray and average energy is significant, but even electric cars using gray energy are causing less CO2 emissions than comparable cars on gasoline or diesel.
CO2 emissions life cycle car
The indirect and direct CO2 emissions related to usage of the car are not complete without taking into account the CO2 emissions that are caused by producing and recycling the car.
If 100% coal powered energy is used to charge the electric car, the electric car causes 4% less CO2 emissions compared to a similar gasoline or diesel car (TNO, 14 July 2014). Coal powered energy causes 935 grams of CO2 per kWh, the Dutch energy mix causes 355 grams of CO2 per kWh (TNO, 14 July 2014) (co2emissiefactoren.nl, January 2015).
Research from TNO shows that electric cars have less CO2 emissions than hybrid-cars and gasoline and diesel cars. The research takes the life cycle of the car into account, from producing to recycling. Looking at the life cycle of the car, an electric car causes 35% less CO2 emissions compared to a similar gasoline or diesel car (TNO, 7 April 2015).
Looking at the electricity production by source, it is safe to say The Netherlands has relatively gray energy. Figure 4 provides an overview of the electricity production by source for Europe and the individual countries (Eurostat, 9 November 2015).
It is safe to say The Netherlands is producing a relatively high percentage of its energy by conventional thermal sources (mostly coal and natural gas) compared to the rest of Europe. This means that the CO2 emissions per kWh are relatively high in The Netherlands. Having this information, it can be said that electric cars are causing less CO2 emissions in Europe than in The Netherlands.
In The Netherlands the electric car, using gray energy, is causing significantly less CO2 emissions than a similar gasoline or diesel car. So, electric cars cause less CO2 emissions than similar gasoline and diesel cars.
A point of discussion that is not yet discussed, is the CO2 emission factor for electricity that is reported by some organisations to calculate the CO2 emissions of electric cars. This CO2 emission factor is based on gray energy and therefore provides the highest possible CO2 emissions for electric cars. As mentioned before, gray energy comprises of coal, natural gas and nuclear power. Since the average energy mix is also comprised of renewable energy sources, using gray energy is misleading. For gasoline and diesel there is no room for discussion, since there is (in essence) only one type of gasoline and one type of diesel.
It is unfair and misleading to use the gray energy emission to calculate the CO2 emissions of an electric car. It is less unfair to use the CO2 emission of the average energy mix, although that is still not considering electric cars that only use renewable energy.
Individuals who would like to calculate their CO2 emissions caused by the usage of their cars, are advised to use the CO2 emission that reported on their energy label. This CO2 emission is the most accurate since it comes directly from the supplier.
CBS. (February 2015). Elektriciteit in Nederland. Consulted on 2 February 2016, from: http://www.cbs.nl/NR/rdonlyres/D694C055-66E0-49D4-A0EA-7F9C07E3861E/0/2015elektriciteitinnederland.pdf
Co2emissiefactoren.nl. (January 2015). Lijst emissiefactoren. Consulted on 1 February 2016, from: http://co2emissiefactoren.nl/lijst-emissiefactoren/#brandstoffen_voertuigen
EcoTest. (13 January 2015). EcoTest Testing and Assesment Protocol. Consulted on 2 February 2016, from: http://www.ecotest.eu/html/EcoTest_Protocol_EN.pdf
European Commission. (23-24 February 2015). JEC Well-to-Wheels: considerations on methodology choices. Downloaded on 1 February 2016, from: https://www.concawe.eu/uploads/Modules/Events/Laura%20Lonza_JRC_Concawe%20Symposium.pdf
Eurostat. (9 November 2015). Electricity production and supply statistics. Consulted on 7 February 2016, from: http://ec.europa.eu/eurostat/statistics-explained/index.php/Electricity_production_and_supply_statistics
TNO. (14 July 2014). Indirecte en directe CO2-uitstoot van elektrische personenauto’s. Consulted on 2 February 2016, from: https://www.tno.nl/media/4404/tno-2014-notitie-directe-en-indirecte-emissie-elektr-voertuig_-14072014.pdf
TNO. (7 April 2015). Energie- en milieu-aspecten van elektrische personenvoertuigen. Consulted on 2 February 2016, from: https://www.rvo.nl/sites/default/files/2015/04/TNO%20Factsheets%20Elektrische%20Voertuigen.pdf
Yushift.com. (20 January 2016). Best verkochte elektrische en plug-in hybride auto’s. Consulted on 2 February 2016, from: http://yushift.com/magazine/best-verkochte-elektrische-en-plug-hybride-autos
Picture of Tesla Model X Signature Red comes from user “vangogh” on the Tesla Motors Club forum via this link: http://www.teslamotorsclub.com/showthread.php/60419-Signature-Red-Model-X-Photos?p=1358701&viewfull=1#post1358701